Protective device for electrical



(No Model.)

J. J. OGONNELL. PROTECTIVE DEVICE FOR ELECTRICAL APPLIANCES.

No. 536,095. Patented Mar. 19-, 1895.

Hg J.

UNITED STATES PATENT OEEIcE.

JOSEPH J. OCONNELL, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE AMERICAN BELL TELEPHONE COMPANY, OF BOSTON, MASSACHUSETTS.

PROTECTIVE DEVICE FOR ELECTRiOAL APPLlANCES.

STPECIFICATION forming part of Letters Patent No. 536,095, dated March 19, 1 895.

Application filed November 23, 1894. Serial No. 529,776. (No modeld T aZZ whom it may concern: vention aims to obviate this trouble and to pre- Be it known that I, JOSEPH J. OCQNNELL, vent the disintegrated particles from forming residing at Chicago, in the county of Cook a cross connection or conductive bridge beand State of Illinois, have invented certain tween the plates by confining them near the Improvements in Protective Devices for Elecface of the plate from which they have be- }5 trical Appliances, of which the following is a come detached, thus preventing them from specification. coming in contact with the opposite plate.

Thisinvention relates to appliances for the I accomplish this result by interposing beprotection of apparatus connected with electween the plates (with the mica strip) a sup- [0 tric circuits from the destructive orinjurious plementary or auxiliary piece, or sheet of effects of strong intrusive currents or charges textile fabric or similar thin sieve like mateof electricity coming upon the line wires from rial, such as silk sufliciently porous and loose any source or cause; and especially to that in its texture to allow the passage of disclass of protectors operating by means of a charges of electricity but fine enough to pre- [5 disruptive discharge through a thin air vent the disintegrated particles from falling In apparatus of this class, usually denomithrough. I use a piece of such material nated lightning arresters, two plates are emslightly longer and wider than the plates, and ployed, one of which is in the line, while the secure it between the plates so that it shall other is separated sl ghtly from the first by not sag down, but be perfectly straight and 20 a thin di-electric, usually of air, and is contaut, and when the plates are placed in their nected to the earth to furnish a path for the supports the latter not only hold the plates escape of a disruptive discharge. The said steady, but also maintain the sieve or sitter plates are made of metal or carbon,preferably in proper tension, all of which will be more the latter,and it is usual when carbon is used, specifically described in connection with the 25 to make them in the form of oblong blocks, drawings, in which two of which are placed together, their par- Figure 1 represents a perspective view of allel faces being separated by a thin strip of alightning arrester embodying the invention. di-electric, as mica, having its central portion Fig. 2 is a section on line m 00 of Fig. 1. Fig. 3 cut out. The plates are mounted in supports shows the mica strip. Fig. 4 shows the sieve;

0 or spring clips provided with binding posts and Fig. 5 shows the arr-ester as arranged in So by means of which they may be connected in an electric circuit. the circuits. In some forms of arrester, a In the drawings, a, is a base board of insuhole is made in the face of one or both of the lating material upon which are secured the carbon plates and a drop of fusible metal, or supports or metal spring clips I) and 0, each 3 5 alloy, placed therein to assist in earthing forof which has a flat part resting upon the base 8 5 eign currents of a dangerous potential, as is board and secured thereto by the binding fully set forth in United States Patent No. posts 5, 6, 7, 8.

438,788. It has been found when disruptive The clip 1) consists of two springs 1 and 2, discharges take place from one plate to anas shown, bent upward and downward with 0 other, that particles of the material of one ledges 9 9 for a plate C to rest upon, and the plate are disintegrated therefrom, and carclip 0 consists of two springs 3, at extending ried to the opposite plate, and if the earth upward with a bend to form ledges 10, 10, for seeking charge is long continued, especially a plate C to rest upon. The distance between when carbon plates are used, a conductive the clip springs 1, 3 and 2, 4; is such that the 5 connection is established between the plates plates C, C have to be pressed in with conby means of these particles; and if this does siderable force. not happen at once,the slight space between I have shown in the drawings plates comthe plates becomes more or less filled with posed of long narrow blocks of carbon, each the particles of carbon and is liable at any having a drop of fusible metal or alloy m in- 50 time to form such a cross connection. My insorted in its face.

I, l l l l M is a strip of mica having its central portion cut out and is slightly longer and wider than the carbon plates C C and of a thickness to provide an air space which will permit the passage of discharges of minimum potentials, usually about thirty five tenthousandths (.0035) of an inch.

S represents the sieve, separator or sitter, which is preferably made of silk, slightly longer and wider than the plates C Then the plates 0 C are to be inserted between the spring clips, the silk piece and micastrip are placed between the said plates, the silk being very carefully straightened out so that it will not sag down, and the whole forced between the clips, as shown.

Should the spark caused by discharge from one plate to the other develop into an arc and continue for a sufficient length of time to heat the plate to the temperature at which the fusible material m melts, the fused material runs into the space between the plates 0 C bridging such space and forming a direct electrical connection between them. The interstices of the piece of silk or other material are sufficiently large to permit of this direct con nection taking place, and the operation of the whole device in this case is substantially as described in Letters Patent No. 438,788 before referred to.

Fig. shows a line Wire L extending to the elipc of a lightning arrester, after passing through a fuse wiref, and thence to earth through the instrument I, to be protected.

The clip I) is connected to earth by wire 00. The operation is obvious.

I claim 1. A potential discharging protector comprising in combination two conducting plates placed with parallel surfaces closely adjacent to each other but separated for a portion of their area by a thin air space, said plates being adapted for connection respectively with an electric circuit and with the earth, and a supplementary interposed piece of textile fabric or similar sieve-like material, adapted to intercept disintegrated particles but offering no impediment to the disruptive discharge across the air-space, substantially as described.

2. A potential-discharging protector comprising in combination, two conducting plates placed with parallel surfaces closely adjacent and adapted to be connected respectively with an electric circuit and with the earth, an in termediate dielectric strip such as mica, having a portion cut away so as to present a thin air space between the two plates, and an anxiliary interposed strip of sieve-like material, such as thin silk, substantially as described.

In testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses, this th day of November, 18%.

JOSEPH J. OCONNELL.

Witnesses:

A. A. THOMAS, A. B. RAYMOND.

I l J 

